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Welded nozzles and flanges of heat exchange unit

Release time:

2025-06-29

In heat exchange units, the connection between welded nozzles and flanges is a common and crucial step, mainly used for the pipe interfaces in the heat exchange system.

Core concept

Welded connection: This is a method of directly welding pipes or connections onto the shell or tube plate of the heat exchanger unit, providing a permanent and high-strength sealing connection. It is suitable for high-temperature, high-pressure or corrosive environments. The advantages are good sealing performance and stable structure, but once the welding is completed, it is not easy to disassemble.

Flanged connection: The flange is a detachable joint, usually fixed to the end of the connection pipe with bolts, facilitating connection with external pipes or equipment. The advantage is that it is easy for maintenance, inspection and replacement, but ensure that the bolts are tightened properly to avoid leakage.

Combined application: In heat exchanger units, the connection pipes are usually first welded to the main body of the equipment, and then flanges are added at the ends. This design takes into account both sealing and maintainability. For example, during cleaning or maintenance, only the flange part needs to be removed without affecting the welded connection.

Key Considerations

1.Welding Quality:

Use standard welding techniques (such as argon arc welding or electric arc welding) to ensure that the welds are free from cracks, pores, or incomplete fusion.

Follow relevant standards (such as ASME B31.3 or GB/T standards), and control the heat input to avoid deformation in the heat-affected zone.

2.Flange selection:

Choose the appropriate type (such as plain weld flange or butt weld flange), ensuring that the flange pressure rating, size, and system match (common standards: ANSI or HG/T).

Flange surface treatment: Use gaskets (such as graphite or metal wound gaskets) to enhance sealing, and regularly check the bolt torque.

3.Installation and Maintenance:

During installation, ensure that the connection pipe and the flange are properly aligned to avoid additional stress, as this could lead to leakage or fatigue failure.

Conduct non-destructive tests (such as radiographic testing) on a regular basis, especially for corrosive media (such as water or chemical fluids).

In high-temperature applications, consider thermal expansion compensation design (such as using expansion joints).